@article{GDZPPN00232816X, title = {Planar Geodesic Immersions in Pseudo-Euclidean Space.}, journal = {Mathematische Annalen}, volume = {275}, year = {1986}, pages = {585-598}, zbl = {0572.53042}, url = {http://dml.mathdoc.fr/item/GDZPPN00232816X} }
Blomstrom, Carol. Planar Geodesic Immersions in Pseudo-Euclidean Space.. Mathematische Annalen, Tome 275 (1986) pp. 585-598. http://gdmltest.u-ga.fr/item/GDZPPN00232816X/